DE 296 12 054 discloses an autostereoscopic display system having a display and a screen arranged at the viewing end of the display. The screen has a plurality of cylindrical lenses. The actual position of the viewer in front of the recording system is determined by a head tracker system and the screen is displaced relative to the display such that the viewer can discern a stereoscopic image from the instantaneous position. The movement of the screen takes place relative to the display in such a manner that the right eye of the observer views only the image gaps, which are assigned to the right sectional image, and the left eye of the viewer views only the image gaps of the display assigned to the left sectional image.
A similar autostereoscopic display system is known from U.S. Pat. No. 5,457,574 wherein the position of the viewer forward of the recording system is likewise determined by means of a head tracker. However, here, the position of the screen is not moved relative to the display in correspondence to the actual viewer position; instead, the light source rearward of the display is switched so that the viewer perceives an autostereoscopic image in his actual viewing position. Furthermore, in this patent, it is already suggested that the output signal of the head tracker be utilized simultaneously to also select the shown view in that, for example, two video cameras are moved in correspondence to the head movements of the viewer. With the video cameras, the stereoscopic partial views are recorded. More details with reference to the movement of the cameras in dependence upon the viewer position or the position of the head of the viewer are not presented in this patent.
A camera system for a robot is known from U.S. Pat. No. 4,818,858. The camera system includes two video cameras which execute mutually opposing rotational movements about the same angle relative to a base.
With the aid of a triangulation system, which is integrated into the cameras, the focussing of both cameras and the convergence of the optical axes of both cameras are simultaneously so controlled that the object to be viewed lies in the intersect point of the two optical axes of the two cameras and both cameras are simultaneously focussed onto this intersect point. The stereo image recorded by both cameras is presented to a viewer on a stereoscopic display system. The observer wears a helmet having sensors which detect the head movement of the observer and their output signals are utilized to control the robot with the stereoscopic camera system.
An important characteristic of the human stereoscopic vision is the coupling of the convergence angle of the two eyes in dependence upon the desired viewing distance. For a large viewing distance, the optical axes of both eyes are aligned almost parallel with the result that objects, which lie farther from the observer, can be viewed stereoscopically. For close viewing, the two eyeballs are rotated in opposite directions toward each other so that the optical axes of both eyes are very convergent with the result that the close lying objects can be perceived stereoscopically.